Joël de Maere d’Aertrycke and Thomas Vermer join Belgian tax law firm, Advisius


Advisius, a Belgian law firm specialising in international taxation, has announced the arrival of Joël de Maere d’Aertrycke as partner and Thomas Vermer as counsel.

Joël de Maere has more than 25 years of experience in international taxation. He spent 12 years in the tax departments of major international audit and consulting firms (Coopers & Lybrand, Andersen, Deloitte), before spending 16 years as an associate tax advisor with the Brussels firm Tax Consult.

He has extensive experience in setting up incentive plans for managers and employees of listed and unlisted companies, including share award plans, stock option plans, warrant plans, profit-sharing plans, and more. He is frequently involved in LBO/MBO transactions. He has also negotiated agreements with the tax authorities (rulings) concerning particularly complex management incentive plans (sweet equity, ratchet shares, carried interest, etc.), for which he has a deep understanding of the financial aspects.

Joël de Maere and his team also advise individuals on the taxation of their income from assets and the transfer of their assets, specifically in multi-jurisdictional situations.

Joël de Maere holds a law degree (UCL) and an additional diploma in tax law (KUL).  He has been a member of the Brussels Bar since 2024.

Thomas Vermer’s practice focuses on advising individuals (shareholders) and their companies on direct and indirect tax matters, particularly in relation to the structuring of their professional income, assets and investments. He regularly advises on complex issues relating to Cayman tax, structured financial products and management packages (stock options). His expertise covers both Belgian and international taxation.

Prior to joining Advisius, he practised tax law for over 10 years with the Brussels firm Tax Consult.

Thomas Vermer is also a lecturer at Ephec (corporate tax and taxation of professional income) and a lecturer in the Executive Master in Tax Management at Solvay Business School (tax on non-resident individuals).

Thomas holds a master’s degree in law (UCL), a bachelor’s degree in philosophy (USLB) and an additional diploma in tax law from the ULB Faculty of Law.  He has been a member of the Brussels Bar since 2024.

Laurent Donnay de Casteau, founding partner of the firm, commented:

“The arrival of Joël and Thomas marks another significant step in the continued growth of Advisius, which is already widely recognized for its expertise in Belgian and international taxation. Their specialization not only enhances the firm’s existing expertise, but also reaffirms our commitment to client excellence.

Joël and Thomas’ approach, which combines pragmatism and a high level of technical expertise, is perfectly in tune with the firm’s DNA. Thomas’s academic duties add a valuable extra dimension to our practice. Their arrival, combined with the strengthening of our team of young associates, means that we now have a team of tax lawyers that few other firms in Belgium can match. This growth consolidates our position and confirms our ambitions for the future.”


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